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Phalcon Interview Questions and Answers

By Admin
Last update: 11 Oct 2019, 18 Questions
Phalcon Interview Questions

Most Frequently Asked Phalcon Interview Questions

Here in this article, we will be listing frequently asked Phalcon Interview Questions and Answers with the belief that they will be helpful for you to gain higher marks. Also, to let you know that this article has been written under the guidance of industry professionals and covered all the current competencies.

1. What is Phalcon and why it is used?

Phalcon is a full-stack open source framework written in PHP and C (programming languages). It is the first framework that implements object-relational-mapping (ORM) in C. This loosely coupled framework is based on MVC (model-view-controller) architecture. Phalcon runs on PHP 5.4 and is one of the fastest frameworks. Phalcon can be used for end to end web applications that

  • Need to be super-fast and handle more HTTP requests per second
  • Consume less resource (hardware) storage as the C extensions are loaded along with PHP during the web-server start process and are pre-compiled.
2. Explain the features of Phalcon?
Following are the unique features of Phalcon –
  • Fastest full stack framework for PHP
  • Low memory and CPU consumption
  • Supports the standard MVC directory structure.
  • Loosely coupled, the user can use the full framework or use only the required components.
  • Uses Dependency injection pattern for faster location of services
  • First framework to implement ORM (Object-Relational-Mapping)
3. What is PHQL in Phalcon? PHQL is a high-level, object-oriented query language similar to SQL. Phalcon provides a parser written in C that translates syntax into RDBMS. This in-memory parser uses the same technology as SQLite, which is thread-safe, prevents SQL injection and consumes very less memory, thus giving high performance.
4. How to increase the CSRF timeout in Phalcon?

In Phalcon, we can increase CSRF (Cross-Site Request Forgery) timeout by increasing the token time as tokens maintain the user sessions. Token time is valid until the session is valid. The session time can be increased by setting session.gc_maxlifetime to a higher value in the php.ini file.

5. What is ODM in Phalcon?

ODM or Object-Document-Mapping is the mapping for NoSQL databases. Phalcon can map documents from NoSQL databases through ODM using a unique ObjectID for each object to be mapped. Phalcon’s ODM offers CRUD functionality, events, validation, and other services. The advantage of ODM is that it is a persistence mechanism where an application model and data source have no dependencies on each other.

6. Please explain dependency injection in Phalcon?

Dependency Injection (DI) is a pattern through which appropriate objects or instances of a class are created during run-time rather than compile-time. The class, thus, becomes independent from creating the cases and it is the responsibility of DI to know which class requires what objects and provide the same. In Phalcon, the DI component implements dependency injection and manages the global instances of different classes used in the application.

7. Please explain Phalcon Routing?

In Phalcon, routing is managed by its Router component. This component allows the user to define and add custom routes that can be mapped to controllers or handlers that receive the requests from the application. The router parses the incoming URI based on the information received.

8. How to use session in Phalcon?

To initiate new session,

  • $session = new Session();
  • $session->start();

setting data into session

  • $this->session->set("key", "value");

retrieve session data

  • $this->session->get(“key”);

removing session

  • $this->session->remove(“key”'); //remove particular variable
  • $this->session->destroy(); //remove the session
9. What is Lazy Initialization in Phalcon?

Lazy initialization is a technique where a class is automatically loaded by the Phalcon class ‘Loader’ during runtime. This greatly improves performance. Auto loader does this in 4 ways i.e. by registering

  • namespaces, $loader->registerNamespaces(…)
  • directories, $loader->registerDirs(…)
  • classes, $loader->registerClasses(…)
  • files $loader->registerFiles(…)

and then registering the auto loader as $loader->register();

10. Which template engine is used in Phalcon? Explain

Volt is the template engine used in Phalcon. It is fast and designer-friendly. Volt views are compiled in php and have many helpers that make writing views easier and quicker.

11. How to inject services into a Volt Template in Phalcon?
There are 2 ways to inject services into Volt -
  • Define the function in the dependency injection container. Access the service in the template with its name. Example - <input name="‘counter’" value="‘{{maxproduct.getCounter()" }}>
  • When Volt is used as a stand-alone component, create a compiler as $compiler = new VoltCompiler(); and compile the template by passing different return parameters.
12. How can you pass data from the controller to view in Phalcon?

You can use setVar() or setVars() in the controller’s showAction() method to pass single or multiple variables respectively, directly to the view.

  • $this->view->setVar('productId', $productId);
  • $this->view->setVars( ['username' => $user->username, 'phone' => $contact->phone,] );

Instead of using the above methods, you can also set the variables as $this->view->username = $user->username;

13. How many database engines supported by Phalcon?

There are 3 database engines supported by Phalcon – Mysql, Postgresql, and SQLite.

14. Explain the differences between Phalcon and Laravel?
S.no PHALCON LARAVEL
1. is a php extension written in C, which is injected into the php core at runtime is a source base on which web developers build their applications
2. offers high performance and fast execution is slower and can process fewer requests compared to Phalcon
3. uses ODM which is fast and has a simple, understandable syntax relies on ORM which supports almost all the databases
4. uses the Volt template engine uses Blade template engine
5. requires root access to be installed doesn’t need root access
6. has fewer forum exchanges and documentation compared to Laravel has a more significant community and more support documentation
15. List the type of views in Phalcon?
There are two types of views in Phalcon –
  • Volt – used when the template engine is written in C and compiled in php, can be used as a stand-alone component.
  • Phtml – used when the template engine is in php itself.
16. Explain the differences between .volt and .phtml files?
  • .volt files are written in C language and later compiled to php code. These can be used as a stand-alone component and includes a set of highly integrated elements.
  • .phtml files should be created when php is used as a template engine. The view is the default rendering component and is called to execute a particular action. .phtml cannot be used as a stand-alone component.
17. How to declare a variable in Phalcon?

No need to declare a variable in Phalcon; the variable is created when its value is assigned. Example - $name = “user1”;

18. What are Single or Multi-Module Applications in Phalcon?

Single module applications have only one module. This application does not mandate a namespace. It has a structure as –

single/

app/

controllers/

models/

views/

public/

css/

img/

js/

Multi-module uses the same document root for all the modules. Each directory in apps has an MVC structure of its own. Module-specific settings are configured using Module.php present in each module. The structure is like –

multiple/

apps/

frontend/

controllers/

models/

views/

Module.php backend/

controllers/

models/

views/

Module.php public/

css/

img/

js/